Purchased the battery January 2009 and i noticed yesterday while testing it one of the cells died. went to interstate yesterday and they confirmed it so i got a brand new one free if charge. I'm disappointed but ill continue using them but will pay closer attention on monitoring the cells and water level for now on.

 

Thats sucks, but its just one of those things that can happen for no reason. Atleast they replaced for free, thats always a good thing.